PROJECT SUMMARY/ABSTRACT The goal of tobacco regulations is to improve public health. Tobacco regulations, however, are often implemented before they have been tested in a research setting, thereby increasing the likelihood of untoward effects caused by such regulations. The goal of this project is to use the Experimental Tobacco Marketplace to empirically assess the effects of regulatory changes on tobacco consumption among smokers. The specific aims will address how factors such as dose, price, environmental constraints (smoke-free work environments), and flavors affect consumption and substitutability of cigarettes and vaporized nicotine products. In these within-subject studies, the research team will examine choices in the Experimental Tobacco Marketplace with some purchases actualized. This novel method will increase the external validity of modern regulatory science. Moreover, the obtained results will help direct policymakers' decisions about the availability and pricing of alternative, potentially less harmful, tobacco products.